Processing of delafossite CuAlO2 ceramic targets by solid state synthesis route
Аутори
Vojisavljević, KatarinaMalič, Barbara
Mamoru, Senna
Kuscer, Danjela
Drnovšek, Silvo
Kosec, Marija
Конференцијски прилог (Објављена верзија)
Метаподаци
Приказ свих података о документуАпстракт
In the past two decades, a considerable effort has been devoted to the study and development of different n- and p-type oxide semiconductors for transparent electronics applications. The p-type delafossite materials CuMO2 (M = Al, Cr or Y) with the band gap above 3 eV, which allows high transparency across the entire visible region, are of particular interest. Copper aluminate (CuAlO2) films prepared by physical vapour deposition have been reported to exhibit the p-type behaviour and have already been used in various applications in optoelectronics. Phase-pure targets with a high relative density are prerequisites for physical vapour deposition of high quality CuAlO2 films. However, secondary phases and low relative densities have been reported for the solid-state synthesized delafossite CuAlO2 although high processing temperatures and extremely long times have been used [1, 2].
The aim of this work has been to prepare the phase pure delafossite powders and dense ceramics by solid-sta...te synthesis. Instead of the usually reported α-alumina (α-Al2O3), we introduced the nano-sized boehmite µ-AlOOH.xH2O powder as an aluminium source, for two reasons, i.e., for its high specific surface area and a consequent large number of contacts with Cu2O particles and for higher reactivity as a consequence of the thermal decomposition (Hedvall effect) as compared to the oxide. Furthermore, the role of different atmospheres, namely inert (Ar) and oxidising (air), has been explored.
The solid-state reaction between nano-Al2O3 and Cu2O (up to ≈ 1 µm in size) at 1100oC in argon resulted in the delafossite phase with appreciable quantities of both unreacted oxides even after 24 h of heating. In contrast, phase pure delafossite powder was synthesized upon heating the nano-boehmite and Cu2O powder mixture for 2 x 10 h at 1100oC in inert Ar atmosphere as confirmed by XRD. The powder consisted of loose agglomerates of plate-like particles of a few 100 nm in size. Heating in air resulted in formation of the spinel CuAl2O4 and CuO phases beside the delafossite in both cases.
The ceramic with 86% of theoretical density has been obtained after sintering the boehmite-derived CuAlO2 powder compact at 1100oC for 2h in air. According to XRD the ceramic was single-phase delafossite. However SEM /EDXS analysis revealed traces of Cu-rich impurities at the surface of the pellet. The bulk of the sample revealed a dense microstructure with a uniform distribution of porosity within the delafossite matrix.
References
[1] H. G. Zheng, K. Taniguchi, A. Takahashi, Y. Liu, C. N. Xu, Appl. Phys. Lett., 85, 1728 (2004).
[2] Y. -C. Liou, U. -R. Lee, J. Alloys Comp., 467, 496 (2009).
Acknowledgement
We acknowledge for funding the 7.FP ORAMA (NMP2-LA-2010-246334: Oxide materials for electronics applications).
Кључне речи:
CuAlO2 / solid-state synthesis / SEM / EDXS / XRDИзвор:
4th Symposium on Transparent Conductive Materials, 21-26 October 2012, Crete, Greece, 2012Институција/група
Institut za multidisciplinarna istraživanjaTY - CONF AU - Vojisavljević, Katarina AU - Malič, Barbara AU - Mamoru, Senna AU - Kuscer, Danjela AU - Drnovšek, Silvo AU - Kosec, Marija PY - 2012 UR - http://rimsi.imsi.bg.ac.rs/handle/123456789/2918 AB - In the past two decades, a considerable effort has been devoted to the study and development of different n- and p-type oxide semiconductors for transparent electronics applications. The p-type delafossite materials CuMO2 (M = Al, Cr or Y) with the band gap above 3 eV, which allows high transparency across the entire visible region, are of particular interest. Copper aluminate (CuAlO2) films prepared by physical vapour deposition have been reported to exhibit the p-type behaviour and have already been used in various applications in optoelectronics. Phase-pure targets with a high relative density are prerequisites for physical vapour deposition of high quality CuAlO2 films. However, secondary phases and low relative densities have been reported for the solid-state synthesized delafossite CuAlO2 although high processing temperatures and extremely long times have been used [1, 2]. The aim of this work has been to prepare the phase pure delafossite powders and dense ceramics by solid-state synthesis. Instead of the usually reported α-alumina (α-Al2O3), we introduced the nano-sized boehmite µ-AlOOH.xH2O powder as an aluminium source, for two reasons, i.e., for its high specific surface area and a consequent large number of contacts with Cu2O particles and for higher reactivity as a consequence of the thermal decomposition (Hedvall effect) as compared to the oxide. Furthermore, the role of different atmospheres, namely inert (Ar) and oxidising (air), has been explored. The solid-state reaction between nano-Al2O3 and Cu2O (up to ≈ 1 µm in size) at 1100oC in argon resulted in the delafossite phase with appreciable quantities of both unreacted oxides even after 24 h of heating. In contrast, phase pure delafossite powder was synthesized upon heating the nano-boehmite and Cu2O powder mixture for 2 x 10 h at 1100oC in inert Ar atmosphere as confirmed by XRD. The powder consisted of loose agglomerates of plate-like particles of a few 100 nm in size. Heating in air resulted in formation of the spinel CuAl2O4 and CuO phases beside the delafossite in both cases. The ceramic with 86% of theoretical density has been obtained after sintering the boehmite-derived CuAlO2 powder compact at 1100oC for 2h in air. According to XRD the ceramic was single-phase delafossite. However SEM /EDXS analysis revealed traces of Cu-rich impurities at the surface of the pellet. The bulk of the sample revealed a dense microstructure with a uniform distribution of porosity within the delafossite matrix. References [1] H. G. Zheng, K. Taniguchi, A. Takahashi, Y. Liu, C. N. Xu, Appl. Phys. Lett., 85, 1728 (2004). [2] Y. -C. Liou, U. -R. Lee, J. Alloys Comp., 467, 496 (2009). Acknowledgement We acknowledge for funding the 7.FP ORAMA (NMP2-LA-2010-246334: Oxide materials for electronics applications). C3 - 4th Symposium on Transparent Conductive Materials, 21-26 October 2012, Crete, Greece T1 - Processing of delafossite CuAlO2 ceramic targets by solid state synthesis route UR - https://hdl.handle.net/21.15107/rcub_rimsi_2918 ER -
@conference{ author = "Vojisavljević, Katarina and Malič, Barbara and Mamoru, Senna and Kuscer, Danjela and Drnovšek, Silvo and Kosec, Marija", year = "2012", abstract = "In the past two decades, a considerable effort has been devoted to the study and development of different n- and p-type oxide semiconductors for transparent electronics applications. The p-type delafossite materials CuMO2 (M = Al, Cr or Y) with the band gap above 3 eV, which allows high transparency across the entire visible region, are of particular interest. Copper aluminate (CuAlO2) films prepared by physical vapour deposition have been reported to exhibit the p-type behaviour and have already been used in various applications in optoelectronics. Phase-pure targets with a high relative density are prerequisites for physical vapour deposition of high quality CuAlO2 films. However, secondary phases and low relative densities have been reported for the solid-state synthesized delafossite CuAlO2 although high processing temperatures and extremely long times have been used [1, 2]. The aim of this work has been to prepare the phase pure delafossite powders and dense ceramics by solid-state synthesis. Instead of the usually reported α-alumina (α-Al2O3), we introduced the nano-sized boehmite µ-AlOOH.xH2O powder as an aluminium source, for two reasons, i.e., for its high specific surface area and a consequent large number of contacts with Cu2O particles and for higher reactivity as a consequence of the thermal decomposition (Hedvall effect) as compared to the oxide. Furthermore, the role of different atmospheres, namely inert (Ar) and oxidising (air), has been explored. The solid-state reaction between nano-Al2O3 and Cu2O (up to ≈ 1 µm in size) at 1100oC in argon resulted in the delafossite phase with appreciable quantities of both unreacted oxides even after 24 h of heating. In contrast, phase pure delafossite powder was synthesized upon heating the nano-boehmite and Cu2O powder mixture for 2 x 10 h at 1100oC in inert Ar atmosphere as confirmed by XRD. The powder consisted of loose agglomerates of plate-like particles of a few 100 nm in size. Heating in air resulted in formation of the spinel CuAl2O4 and CuO phases beside the delafossite in both cases. The ceramic with 86% of theoretical density has been obtained after sintering the boehmite-derived CuAlO2 powder compact at 1100oC for 2h in air. According to XRD the ceramic was single-phase delafossite. However SEM /EDXS analysis revealed traces of Cu-rich impurities at the surface of the pellet. The bulk of the sample revealed a dense microstructure with a uniform distribution of porosity within the delafossite matrix. References [1] H. G. Zheng, K. Taniguchi, A. Takahashi, Y. Liu, C. N. Xu, Appl. Phys. Lett., 85, 1728 (2004). [2] Y. -C. Liou, U. -R. Lee, J. Alloys Comp., 467, 496 (2009). Acknowledgement We acknowledge for funding the 7.FP ORAMA (NMP2-LA-2010-246334: Oxide materials for electronics applications).", journal = "4th Symposium on Transparent Conductive Materials, 21-26 October 2012, Crete, Greece", title = "Processing of delafossite CuAlO2 ceramic targets by solid state synthesis route", url = "https://hdl.handle.net/21.15107/rcub_rimsi_2918" }
Vojisavljević, K., Malič, B., Mamoru, S., Kuscer, D., Drnovšek, S.,& Kosec, M.. (2012). Processing of delafossite CuAlO2 ceramic targets by solid state synthesis route. in 4th Symposium on Transparent Conductive Materials, 21-26 October 2012, Crete, Greece. https://hdl.handle.net/21.15107/rcub_rimsi_2918
Vojisavljević K, Malič B, Mamoru S, Kuscer D, Drnovšek S, Kosec M. Processing of delafossite CuAlO2 ceramic targets by solid state synthesis route. in 4th Symposium on Transparent Conductive Materials, 21-26 October 2012, Crete, Greece. 2012;. https://hdl.handle.net/21.15107/rcub_rimsi_2918 .
Vojisavljević, Katarina, Malič, Barbara, Mamoru, Senna, Kuscer, Danjela, Drnovšek, Silvo, Kosec, Marija, "Processing of delafossite CuAlO2 ceramic targets by solid state synthesis route" in 4th Symposium on Transparent Conductive Materials, 21-26 October 2012, Crete, Greece (2012), https://hdl.handle.net/21.15107/rcub_rimsi_2918 .